The present invention relates to a superimposing circuit of an image apparatus, and more particularly, to a superimposing circuit whereby an RGB signal can be superimposed onto an external image signal in a pixel unit.
An image-song accompaniment apparatus requires high speed superimpose technology for processing lyrics to caption on an external background image signal. Generally, while the external background image signal is an analog signal of NTSC mode, the caption signal is first provided as digital data, and then undergoes a mixing process with respect to the background signal, after being converted into an analog signal by a digital-to-analog converter. Since this mixing process is for overlapping the analog signals, the circuitry is complicated and synchronization with the external image signal is difficult.